WASHINGTON — With the presidential race now three weeks past, the first phase of President-elect Bill Clinton's transition has ended and the second phase--the actual construction of a new government--is about to begin.

For Clinton aides here and in Little Rock, Ark., the main preoccupation for the last three weeks has been putting the machinery of the transition into place--setting up the elaborate network of committees, advisory panels and working groups that are designed to funnel recommendations and policy options to Clinton and his top advisers.

Now, with the final announcements Wednesday of who will head the various "cluster groups" that will audit federal agencies for Clinton and his aides, that machinery is in place. After a brief pause for the Thanksgiving holiday, which probably will be the last break most senior Clinton aides get before the inauguration, the transition teams are expected to begin producing reports and recommendations.

"If you wanted to accurately describe what we've been doing, you'd write, 'Bill Clinton and his aides spent the last few days sitting and thinking about what the government should look like. No decisions were made,' " said one senior adviser.

But that dynamic likely will change soon after the holiday, aides said, noting that Clinton has told them to present options on major issues to him by mid-December and that he is likely to begin naming top Cabinet officers early in December.

Although Clinton has not set a firm timetable, senior advisers said that he would like to have his Cabinet named before Christmas--sticking roughly to the same pace as the last several transitions. Under that timetable, Clinton would move to the final phase of the transition--putting in place his specific agenda for the first 100 days of his Administration--by roughly the beginning of the new year.

Already, the structure that Clinton has created provides some clues to the ideas he has for his Administration.

Clinton's priorities, for example, are clear from the agendas for the four policy teams that he set in place in Little Rock earlier this month. Those teams are working on proposals for the economy, national security, health care and a short list of domestic policy initiatives, such as his proposed national service plan that would allow college students to pay off some of their student loans through public service work.

That list is broad. But even so it leaves aside a host of other issues that will be deferred until the new Cabinet is in place, top aides said.

While those policy teams prepare lengthy sets of options for Clinton on the issues he has decided to concentrate on, the separate agency clusters announced Wednesday will work on preparing briefing papers for the new Cabinet members. Those papers are supposed to concentrate not on broad policy, but on specific lists of short-term problems that Clinton's appointees will find waiting for them as soon as they move into their new offices.

"A lot of the policy decisions won't be made until the new Cabinet members are named," said one Clinton transition aide. "Obviously, you don't want to name a Cabinet member and have him show up on his first day of work and have someone say: 'Here's your program.' "

Instead, the role of the cluster groups announced Wednesday will be to audit each agency in the vast federal bureaucracy. "They're fact finders," said another Clinton aide involved in the process. "It's a bureaucratic task rather than a policy-making task." The idea, the aide explained, is to compile as comprehensive a list as possible of questions that are likely to confront new Cabinet secretaries and agency directors in their first few months on the job.

The top priority will go toward identifying pending regulatory issues and key personnel decisions that could have political repercussions in the early days of the new Administration, the aide said. The job is to "find the land mines," he said.

One other aspect of the transition structure that reflects Clinton's priorities involves the way the transition teams for different agencies have been grouped into clusters.

Clinton has spoken admiringly of how President Bush's chief national security aides--former Secretary of State James A. Baker III, Defense Secretary Dick Cheney and National Security Adviser Brent Scowcroft--worked together as a team, and has pointed out the contrast between their cohesiveness and the fractious nature of Bush's economic team.

One of the priorities for his Administration will be to choose Cabinet members in groups, with an emphasis on finding appointees who will cooperate, Clinton has said.

Whether that plan will avoid the usual bureaucratic turf battles remains to be seen, but as a step toward achieving his goal Clinton has started the transition with a structure in which teams auditing several agencies will each report to a small number of coordinators covering broad regions such as national security policy, natural resources policy or economics.